What have I done wrong? Carcass not square

[Mjward]

Made a perfectly level plinth yday. Made a basic wardrobe carcass, put on said plinth and noticed the carcass wasn't level. A few shims later and it was ok, didn't think much about it.

Today, made another perfectly level plinth. Made a drawer carcass and again noticed it wasn't level. The plastered walls on each side were surprisingly straight and true, which made my carcass look more like a parellelogram than a rectangle.

Something is obviously going wrong at the assembly stage as I've checked all the measurements and everything is spot on to the mm.

So the question I have is, what are you actually doing when screwing in the sides of your carcasses to ensure you're getting those 90 degree angles spot on?

 

[robgul]

Are the boards cut with good square edges?

Using pocket hole joinery is best achieved using corner clamps when assembling - this YT film published today has the sort of clamps I use (buy from Banggood in China - - - shop around for prices) Are you using proper pocket hole screws with a pan head?



What's with the socket blank on the RH side? - I'd have take the plastic plate off and made a 3mm plywood plate that screwed to the wall box and was flush to the plaster surface - thus being able to make the cabinet full width as a tight fit.

 

[HOJ]

Did you measure the diagonals of carcass to check for square?. + I would also suggest fitting corner leg supports on the plinth, even just bits of 2" * 2" screwed on would do.

 

[williams1185]

first off is the base level in all planes ? usually when fitting the carcase leave a space each side to scribe in an infill piece dont trust a level , walls are not that perfect as long as the box is square . Try your level on the vertical sides if thats ok then the walls are out .

 

[Doug71]

Well for a start I wouldn't trust that square you are using

As said if all your lengths are equal, your cuts square and corner to corner measurement equal you shouldn't be far off. Looks like you have a back on the cabinet which should hold that square, you can always tack a lath across the front going to opposite corners to hold the front square while you fix it in place.

Are your levels showing true level, spin them round to check.

 

[HOJ]

Well for a start I wouldn't trust that square you are using

Is that what the piece of Lego in the corner is meant to be:

 

[Alli]

Seconded for checking your square is square. When I first started off I bought a set of 3 engineer squares, admittedly they were cheap. After banging my head against the wall as nothing came out square despite how careful I was. I found out that one square was out by a degrees one way, the second was out by a degree the other way and the 3rd was about right. Talk about chasing my tail wondering what was going on!!!!

 

[Spectric]

These are good for clamping as it fits into pocket hole. Kreg Right Angle Clamp with Automaxx

 

[baldkev]

You can make up some squares from ply or mdf offcuts. I have lots at the workshop from 200mm sq to 600mm sq. Plus of course a number of metal squares, which are tested fairly regularly
Edit to add: you cut out the centre of your squares, which can be square shaped or triangular, and use them to clamp into the corners while the workpieces goes off

 

[eribaMotters]

If the corners were 90 degrees when you put it together then you are cutting things square and gluing up correctly.
The one things that stands out to me is the front of your carcase is unsupported/not braced. It will rack [wobble around] and the top member of the carcase will drop in the centre. The result will not be good.
When I make a carcase in plywood [less likely to wobble out of true] or mdf I generally butt it up to the skirting and have a spacing batten fixed to the wall that fill the gap. I fix the carcase to this and as such stop the racking. I then plant a M&T framework onto the front of the carcase. This not only looks nice but also stops the top of the carcase dropping and further resists racking.

Colin

 

[johnnyb]

I'll explain why a small square is useless to get something this size. what can happen is the top and sides can bow leading your tiny square registering against bent stuff. all sides equal then equal sizes corner to corner. same with door frames.

 

[raffo]

Ensure that your floor is flat and the walls perpendicular to it. Fit your carcass to the deviances of the building or cover them.

 

[Jacob]

If the corners were 90 degrees when you put it together then you are cutting things square and gluing up correctly.
The one things that stands out to me is the front of your carcase is unsupported/not braced. It will rack [wobble around] and the top member of the carcase will drop in the centre. The result will not be good.
...........

yep. crops up a lot. The front isn't braced at all but the back is, with a board. So any movement will be at the front.
Pull it straight with a screw or two through the right hand panel, into the wall, with a bit of packing in the right place?

 

[Bristol_Rob]

For me, if you fitted the back panel nice and square. You can make a large tri-square out of an off-cut of MDF.
Say 16"x16" to give a nice big reference. Then clamp that to the top front left hand side. Because you have space to leave that in place while you fix the carcass in place

 

[Mjward]

Wow, what fantastic responses, thanks all, will try and get through all of them:

• Are the boards cut with good square edges? Yup, cut with plunge saw/guide rail and I’m now in the habit of triple checking measurements/square. I’m satisfied the boards themselves are true.
• Knowing the pocket holes screws like to move the piece slightly, my method up to now has been to countersink a pair of screws out the outer face at the top and bottom of where it meets the next board i.e. so I have more control that where the boards meet they are aligned. After they are in I then go around screwing in the pocket holes (using the kreg ones with pan head). Although I’m face palming as Roy’s comment about the Kreg clamp reminded me that I had bought a pair of these last month and they were just sitting on the floor unused.
• I did not measure the diagonals of the carcass. In fact in my novice/amateur approach, I failed to even check a single corner was a 90 degree. In assembly I had put on quick corner clamps, took the view that if the boards were right and the corner clamps were on, then obviously the carcass would be right but clearly that was my fatal error.
• Re the base/plinth, yup that has been triple checked, I am happy in every direction including diagonal that it is level (and have checked the levels themselves). The gap on the right hand side is to scribe an infill piece, I aligned it flush to the left hand wall as will then scribe an infill piece to the chimney breast i.e. scribes on both sides if that makes sense
• Lol that made me giggle…that’s not my main square a recent acquisition (a set of 8) to use along with clamps during assembly of things but in this instance I used Wolfcraft corner clamps which I won’t be doing again. I suspect that the first piece I attached must have come in at a minute angle, which when replicated for the other three corners means the whole thing has a lean that become noticeable at its length. Novice/amateur error no2… I made a squared back panel didn’t I…. put on the carcass and…well…it didn’t line up. No matter how I positioned it, one corner had too much and another not enough etc. Did I dare question the carcass at this stage? Nope… assumed I’d cut the back wrong and flush cut the overhang with the palm router. All that said, I’ve never spent more than a tenner on a square so today’s purchase will be rectifying that. Also as per the suggestion, I think making longer squares with cutouts might help going forward as a way to clamp during assembly.
• Re bracing/racking, this lower carcass is for drawers and then I will put another narrower carcass (long story) on top for a hanging rail. Where the 2x 18mm MR MDF meet will be covered with a similar size 21mm thick Redwood face frame. Additionally, I’ll gripfill the gap most of the height from the carcass to the right hand wall and then put a few nails between the carcass into that piece once it’s gone off to give it more vertical support. You’ve now got me thinking, as it’s quite a wide piece, to also scribe and fill the small horizontal gap at the back of the carcass to really wedge it into place etc

In summary, I’ve made some significant errors but bloody glad I’ve identified them so early in the project. In regards to remedying this current carcass, should I get the hammer out and knock the back off, then disassemble the carcass and start again? (my concerns would be the screws would just find their original holes although might be ok with a much better clamping job. Or as suggested, should I maybe screw the bottom of the carcass into the plinth to give it a footing, then try and “twist” the front true by screwing into the right hand wall?



Once again… honestly and genuinely, thank you all for your help, was the end of a tough week yday and could feel the stress demons approaching. Feel a lot better about going back out there now.

 

[Jacob]

Wow, what fantastic responses, thanks all, will try and get through all of them:

• Are the boards cut with good square edges? Yup, cut with plunge saw/guide rail and I’m now in the habit of triple checking measurements/square. I’m satisfied the boards themselves are true.
• Knowing the pocket holes screws like to move the piece slightly, my method up to now has been to countersink a pair of screws out the outer face at the top and bottom of where it meets the next board i.e. so I have more control that where the boards meet they are aligned. After they are in I then go around screwing in the pocket holes (using the kreg ones with pan head). Although I’m face palming as Roy’s comment about the Kreg clamp reminded me that I had bought a pair of these last month and they were just sitting on the floor unused.
• I did not measure the diagonals of the carcass. In fact in my novice/amateur approach, I failed to even check a single corner was a 90 degree. In assembly I had put on quick corner clamps, took the view that if the boards were right and the corner clamps were on, then obviously the carcass would be right but clearly that was my fatal error.
• Re the base/plinth, yup that has been triple checked, I am happy in every direction including diagonal that it is level (and have checked the levels themselves). The gap on the right hand side is to scribe an infill piece, I aligned it flush to the left hand wall as will then scribe an infill piece to the chimney breast i.e. scribes on both sides if that makes sense
• Lol that made me giggle…that’s not my main square a recent acquisition (a set of 8) to use along with clamps during assembly of things but in this instance I used Wolfcraft corner clamps which I won’t be doing again. I suspect that the first piece I attached must have come in at a minute angle, which when replicated for the other three corners means the whole thing has a lean that become noticeable at its length. Novice/amateur error no2… I made a squared back panel didn’t I…. put on the carcass and…well…it didn’t line up. No matter how I positioned it, one corner had too much and another not enough etc. Did I dare question the carcass at this stage? Nope… assumed I’d cut the back wrong and flush cut the overhang with the palm router. All that said, I’ve never spent more than a tenner on a square so today’s purchase will be rectifying that. Also as per the suggestion, I think making longer squares with cutouts might help going forward as a way to clamp during assembly.
• Re bracing/racking, this lower carcass is for drawers and then I will put another narrower carcass (long story) on top for a hanging rail. Where the 2x 18mm MR MDF meet will be covered with a similar size 21mm thick Redwood face frame. Additionally, I’ll gripfill the gap most of the height from the carcass to the right hand wall and then put a few nails between the carcass into that piece once it’s gone off to give it more vertical support. You’ve now got me thinking, as it’s quite a wide piece, to also scribe and fill the small horizontal gap at the back of the carcass to really wedge it into place etc

In summary, I’ve made some significant errors but bloody glad I’ve identified them so early in the project. In regards to remedying this current carcass, should I get the hammer out and knock the back off, then disassemble the carcass and start again? (my concerns would be the screws would just find their original holes although might be ok with a much better clamping job. Or as suggested, should I maybe screw the bottom of the carcass into the plinth to give it a footing, then try and “twist” the front true by screwing into the right hand wall?



Once again… honestly and genuinely, thank you all for your help, was the end of a tough week yday and could feel the stress demons approaching. Feel a lot better about going back out there now.

Doesn't help that building with mdf and pocket screws is only a step away from building with cardboard and nails! Your top piece should at the very least sit on top of the sides rather than between them. Any weight there and it would bend or break away completely.

 

[Mjward]

Doesn't help that building with mdf and pocket screws is only a step away from building with cardboard and nails! Your top piece should at the very least sit on top of the sides rather than between them. Any weight there and it would bend or break away completely.

It's interesting you say that as the logic in me assumed that would make the most sense but when I started out, my research came back with people saying that the top/bottom boards go between the sides and not on top.

 

[robgul]

Binge watching quite a few of @petermillard YT videos on making cabinets (there's a recent "basic boxes" one) would be helpful for you.

 

[Spectric]

your tiny square registering against bent stuff.

Corner to corners being equal ensures its square, always use the largest square you can to check square edges and the same with spirit levels because you are after the average over the length and not just a small section.

 

[Mjward]

Corner to corners being equal ensures its square, always use the largest square you can to check square edges and the same with spirit levels because you are after the average over the length and not just a small section.

Think this has been a big factor so will start using much larger squares and use clamping squares too